US2921996A

US2921996A - Self-aligning rotary electrical switch

Info

Publication number: US2921996A
Application number: US710734A
Authority: US
Inventors: Donald O Dulude
Original assignee: Kuhlman Electric Co
Current assignee: Kuhlman Electric Co
Priority date: 1958-01-23
Filing date: 1958-01-23
Publication date: 1960-01-19
Anticipated expiration: 1977-01-19

Description

Jan. 19, 1960 D. o. DULUDE 2,921,996

SELF-ALIGNING ROTARY ELECTRICAL SWITCH Filed Jan. 25, 1958 2 Sheets-Sheet 1 INVENTOR. DONALD O. DULUDE ATTORNEYS Jan. 19, 1960 D. o. DULUDE SELF-ALIGNING ROTARY ELECTRICAL SWITCH 2 Sheets-Sheet 2 Filed Jan. 25, 1958 INVENTOR. DONALD O. DULUDE 25m fi l. M WW FIG. 3

ATTORNEYS United States Patent 2,921,996 SELF-ALIGNING ROTARY ELECTRICAL swrrcn Donald 0. Dulude, Rochester, Mich., assignor to Kuhlman Electric Company, Birmingham, Mich., a corporation of Michigan Application January 23, 1958, Serial No. 710,734 3 Claims. Cl. 200-11 This invention relates to. rotary electrical switches and more particularly to a rotary switch construction adapted for use in high potential circuits such as is required of transformer .tap changers, for example, and in which the electrically conductive contact parts of the rotor are self-adjustable to assure uniform contact pressure in the event of misalignment of the contact parts with which the rotor mounted contacts cooperate.

Switches of the general class to which the invention relates and in use heretofore customarily include a'plurality of stationary contacts connected to selected current-carrying parts of electrical apparatus such as a transformer, for example, and mounted on a supporting panel in arcuate or circular form. Such constructions also include a rotatable bridging device composed of one or more generally segment-shaped plates provided with one or more contact parts, the arrangement being such that the contact part or parts on the bridging device are capable of spanning the distance between and engaging any two adjacent stationarycontacts on the panel. In some of the prior switch constructions, the contacts carried by the bridging device have been arranged to straddle a pair of stationary contacts and lie in substantially parallel planes so as to enable magnetic force to add to the mechanical force with which the stationary contacts are gripped by the bridging contacts.

In the known constructions ditficulty has been experienced in obtaining uniform contact pressure between the bridging contacts and the two adjacent contacts of the stationary contacts. One of the principal sources of difiiculty in this respect is due to misalignment of the stationary contacts, that is, one of the stationary contacts may not be in exactly the same plane as the other. When two such misaligned contacts are bridged by the bridging contacts, considerably more pressure will be exerted on one stationary contact than on the other, with the result that excessive wear of the contacts occurs, or infirm engagement is obtained between the bridging contacts and one of the stationary contacts, or both.

An object of the invention is to provide a rotary switch construction which overcomes the disadvantages previously referred to of switches in use heretofore.

Another object of the invention is to provide a rotary switch construction in which the stationary and bridging contact elements are so constructed and arranged as to be capable of relative movement so as to compensate for misalignment of the stationary contacts.

A further object of the invention is to provide a selfaligning rotary switch construction in which the stationary and movable contact elements are capable of substantially universal relative movement within limits so as automatically to assure uniform contact pressure of the movable and stationary contact elements.

Still a further object of the invention is to provide a rotary switch construction of the kind referred to in which the movable bridging contacts are arranged to straddle the stationary contacts and are yieldably urged towards one another so as to grip the stationary contacts therebetween.

Other objects and advantages of the invention will be pointed out specifically or will become apparent from the following description when it is considered in conjunction with the appended claims and the accompanying drawings, in which:

Figure 1 is a view partly in plan and partly in section of the elements of a rotary switch constructed and arranged in accordance with one embodiment of the invention;

Figure 2 is a fragmentary, enlarged elevational view of the apparatus shown in Figure 1;

Figure 3 is an end elevation of one of the movable contact elements supported on its rotor part in accordance with the invention;

Figure 4 is a view similar to Figure 1, but disclosing a modified form of the invention; and

Figure 5 is a fragmentary, enlarged view partly in elevation and partly in section of the construction shown in Figure 4.

Apparatus constructed in accordance with the embodiment of the invention shown in Figures 1 and 2 comprises a mounting panel 1 formed of any suitable insulating material such as laminated nylon, phenolic material such as Bakelite, or any other suitable substance, and on which is mounted a plurality of stationary contact elements 2 formed of suitable electrically conductive material such as copper. As is best shown in Figure 1, the contact elements 2 are arranged in arcuate or circular form and each of the contact elements is mounted on the panel 1 by means of a metallic, headed bolt 3 and an annulus or ring 4 formed of the samematerial as the mounting panel 1. Each of the contact elements 2 and the annulus 4 are provided with aligned openings to accommodate the shanks of the bolts 3, the headed ends of the bolts bearing against the respective contacts 2 and the other end of the bolts being threaded as at 5 for reception of retaining nuts 6. One end of a currentcarrying part 7 leading from a transformer or the like (not shown) also may be connected to each bolt 3 and removably anchored to the latter by an anchor nut 8, whereby the part 7 is electrically connected to the associated contact element 2. Each of the contact elements 2 may have a blind opening 9 therein adapted to register with a similar opening 10 formed in the annulus 4, the openings 9 and 10 normally receiving an anchor pin 11 which reacts between the contact element 2 and the annulus 4 to prevent rotation of the contact element about the axis of the bolt 3.

At the center of the are or circle defined by the several contact elements 2 the mounting panel 1 maybe provided with an opening 12 in which is rotatably mounted a driving shaft 13 which preferably is formed of insulating material similar to that previously referred to. Suitable means such as a crank or wheel (not shown) may be fixed at one end of the driving member 13 for rotating the latter when desired.

In the embodiment of the invention disclosed in Figures 1 andl, the switch includes a bridging device 14 composed of a pair of supporting members or plates 15 formed of non-conductive material of the kind previously referred to and spaced apart from each other. Each of the mounting plates 15 is cut away at one end as at 16 so as to form a pair of leg sections 17 adapted to straddle the driving shaft 13. The leg section 17 of each supporting plate is provided with aligned openings 18 adapted for reception of either a metallic or non-metallic mounting pin 19 which also passes through an opening in the driving shaft 13 so as rockably to connect each mounting plate 15 to the driving shaft for movement with the latter. The

-wall.of the opening .16 so as to enable each plate 15 to partake of'limited rocking movement about the axis of its pin 19. 1f .desired the retention of the pin 19 may be assured by atapered orother suitably constructed locking plin,21 extending through openings in one leg 17 of each indilnting plate 15 and in the pin 19, the latter opening being'located at right angles to the opening18.

The supporting members 15 are so connected to the drive shaft 'lj3that they are superposed and extend radially from the drive shaft towards'tihe are or circle defined by the stationary contact elements 2. The radially outermost end of each of the mounting plates 15 is provided with an extension or jledge '22which projects beyond the remainder of the plate 15 and the outer face of each plate 15 isibored astat 23 for reception of one end of a mounting post 24. Adapted to be mounted on the radially outer end of each mounting plate 15 is a bridging contact member 25 formed of suitable electrically conductive material such as copper and, each contact member 25 is provided with a substantially centrally located bore'26 of'such size as 'r'otatablyto receive the shank of the mounting post 24. The outer end of the post 24 is headed as at 27 so as to prevent inadvertent separation of the contact member 25 and 'the associated mounting plate 15 and the mounting I post'24 is removably retained in assembled relation with its associated mounting plate 15 by means of an anchor pin 28 which extendsthrough aligned openings in the mounting plate and the mounting post 24. The size and arrangement of each of the contact members 25 are such that a'-"smallgap 22a'exists between the member and its associated ledge 22 when the'parts are assembled. The gap 22a permits each contact 25 to be rocked about the axis-of the post 24, for a purpose to be pointed out, and

the rockable mounting of the contacts 25 and the support- I ing' plates 15 enables each contact to partake of substantially universal, but limited movement.

. The spacing of the two mounting plates 15' during normal operating conditions is such that the two adjacent contact elements 2 bridged by the contact members 25 are sandwiched between the latter as is shown in Figure ,2 In the preferredconstruction each of the mountingplates 15 is lockable about the axis of its associated mounting'pin' 19, as has been pointed out, so in order toassure g'oodcontact between the stationary contact ele ments and-both bridging contact members 25, yieldable meansgener'ally indicated by the reference character 29 is incorporated in the apparatus for yieldably biasing the mounting plates 15 and the contact members 25 towards a one another. The biasing means disclosed in Figures 1 and2 may comprisea bolt 30 extending through aligned openings 31 in the mounting plates 15 and having a head 32 atione end adapted to bear against one of the plates 15. The bolt 30 may receive a washer 33 adjacent to its other endcarranged tovbear against the other mounting plate 15 and the boltalso'receives a spring 34 arranged to react between-the washer 33 and a similar washer 33a which may besadjusted longitudinally of the bolt by a threaded nut.35. Adjustment of the nut 35 on the bolt 30 will vary 'theforce with which the mountingplates 15 and their associated contacts 25 are urged towards one another.

In the operation of the embodiment disclosed in Figures '1, 2- and .3; the driving shaft 13 may be rotated so as to cause-the contacts 25 to bridge any two adjacent stationcontacts2 and engage the latter on opposed surfaces as is shown in Figure 2. In an ideal construction, the opposedsurfaces of the-stationary contacts 2 will be perfectly parallel. with each other and with, the surface 1a of the mounting panel 1'. In actual practice, however, the opposed surfaces of the stationary contacts 2'may'not be parallel witheaoh other or with the adjacent surface of the mounting panel,.and the stationary contacts 2 of any given pair .ofacontacts may be somewhat misaligned so 4 V v 7 that they are not located in the same place. In either event, firm contact between the bridging contacts 25 and any two adjacent stationary contacts 2 is assured, due to the ability of each contact 25 to rock about the axis of 'its mounting post 24 which, as is best'illustrated in Figure 7 2, lies in a plane substantially parallel to the plane of the surface In of the longitudinal panel 1. Positive engagement between the bridging contacts and the stationary contacts further is assured bythe yieldable biasing means 29. As a result, good electrical connection between two adjacent stationary contacts 2 is provided.

Rotary switches of the kind to which the invention relates generally are manufactured, carefully, so' the mis aligment of any two adjacent stationary contacts 2 usually will be of fairly small degree. Accordingly, the degree of rocking movement of the movable contacts 25, and the plates 15 need not be great. However, the sizes of the gaps 2i and 22a may be as' large as necessary to produce the desired results. i v t In order to assure smooth operation of the switch when the bridging device is rotated, the ends of the contacts 25 are rounded as at 25a to permit them to ride smoothly over the fixed contacts 2 in either direction of rotation of the drive shaft 13; The contacts 25 also may be rounded as at 25b to avoid the concentration of voltage stresses.

The embodiment of the'invention disclosed in Figures.

2 4 and 5 is generally similar to the embodiment previously described, with the exception of the construction 'of' the piates on which the movable contact elements 25 are mounted. in the modified embodiment of the invention each of the mounting plates 15a is provided with a sub stantially elliptical opening 1611 having; its major axis lying alongthe longitudinal axis of the plate 15a so as to provide a gap Zita between the plate 15a and the driving and. which comprises a shouldered pin 3(lahaving a re duce'd end portion 35 received in an opening 36 in. one

rent passing therethrough to add to the mechanical force.

of'the plates 15a and an enlarged portion 35a received inta'n opening 3''] in the other plate 15a. the pin Silo between the plates 15a is a'spring 38 which bears against each of the plates 15a and urges them in such directions as. to cause the contacts 25tto move to Wards one another and grip the stationary contact ele ments 2 sandwiched therebetween. Retention of the pin Mia may be assured by peening over he free end of the reduced end portion 35 as is'indicatedat 351).

In the construction shown in Figures 4 and 5 the struc ture and arrangement of the mounting plates 15a and the yieldable means 2% are such that the driving shaft 13 is interposed'between the yieldable means and the bridging contacts 25, whereas in the embodiment of the invention shown in Figures 1 and 2 the construction and arrangement of the mounting plates 15 and the yieldable means 29 are such that the yieldable' means is interposed between the drive shaft 13 and the movable contacts 25. v In all other respectahowever, the two embodiments are similar and the operation of the two embodiments is identical.

Apparatus constructed in accordance with either emoodirnent of the invention not only has the desirable characteristics referred to above, but also possesses the advantages of known constructions. For example the contact members 25 are maintained in substantial parallelism so as to enable the magnetic forces created by curby which the stationary contacts are gripped. Furthermore, backlash is not required to obtain the self-aligning action of the contacts 25. Moreover, all electrical energy carrying parts are isolated by insulating materialand aresupported in spaced relation to the mounting panel so as to .minimizethe formation of sludge. An addi- Surrounding tional advantage of the disclosed embodiments is the as to be mounted in an insulated tube, thereby allowing the unit to be nested between the coils of a transformer.

The disclosed embodiments are respresentative of presently preferred forms of the invention, but are intended to be illustrative rather than definitive thereof. The invention is defined in the claims.

I claim:

1. A rotary switch construction comprising a mounting panel; a plurality of electrically conductive contact elements; means mounting said contact elements on said panel in spaced apart, arcuate form and spaced from said panel; a rotary driving element located at the center of the arc defined by said contact elements; apair of spaced apart, superposed, generally parallel support members formed of insulating material and extending radially from said driving element towards the arc defined by said contact elements; pivotal means drivingly mounting each of said support members on said driving element for rotation with the latter about the axis of rotation of said driving element and for-movement of the radially outer ends of said support members towards and away from one another about spaced axes defined by their respective pivotal means; an elongate, electrically conductive contact member for each of said support members and being of such length as to bridge the space between and engage opposite sides of any adjacent two of said contact elements; pivotal means mounting each of said contact members on its respective support member adjacent to the radially outer end thereof for rotation about an axis substantially parallel to and fixed with respect to its respective support member; limit means on each of said support members cooperable with said contact members for limiting rotation of the latter; and yieldable means reacting on said support members remote from said contact members for yieldably urging the radially outer ends thereof and said contact members towards one another.

'2. The construction set forth in claim 1 wherein said yieldable means reacts intermediate said driving element and the radially outer ends of said support members.

3. The construction set forth in claim 1 wherein said supporting members include extensions projecting from the axis of rotation of said driving element in a direction opposite from said radially outer ends, and wherein said yieldable means reacts on said extensions.

References Cited in the file of this patent UNITED STATES PATENTS